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<head>
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  <title>Document</title>
  <link href="https://cdn.bootcss.com/twitter-bootstrap/4.3.1/css/bootstrap-grid.css" rel="stylesheet">
  <style> 
  .border {
    outline: 1px solid black;
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</head>
<body>
  <div class="row">
    <div class="col-sm-1 border"> 内容</div>
    <div class="col-sm-4 border"> 内容</div>
    <div class="col-sm-2 border"> 内容</div>
  </div>
  <div class="row">
    <div class="col-md-4 border">第二</div>
    <div class="col-md-4 border">第二</div>
    <div class="col-md-4 border">第二</div>
  </div>
</body>
</html>